Thermoelectric Circuits and the Performance of Several Aircraft Engine Thermocouples
AIR65
The NET EMF of a thermoelectric circuit can be thought of as originating entirely in the regions of temperature gradient. Any extraneous materials, such as switch or connector terminals, in a temperature gradient may cause an error in the temperature measurement.
In addition to circuitry errors, jet engine thermocouple indications require correction for the effects of conduction, radiation, response rate, and gas velocity. The magnitudes of the corrections depend on the thermocouple design and the environmental conditions. Performance curves for several typical jet engine thermocouples are presented, with the methods of making the various corrections.
Rationale: AIR65 has been superseded by the document AIR46, “The Preparation and Use of Thermocouples for Aircraft Gas Turbine engines”. AIR46 consolidates the contents of this document (AIR65 “Thermoelectric Circuits and the Performance of Several Aircraft”) plus AIR690 “Standard Exposed Junction Thermocouple for Controlled Conduction Errors in Measurement of Air of Exhaust Gast Temperature” and AIR691 “Recommended Ice Bath for Reference Junctions”. As such, AIR46 provides a comprehensive document for testing and calibrating thermocouple components for use in gas turbine engines making the contents of AIR65, AIR690, and AIR691 redundant and unnecessary. This document consolidation strategy was agreed to by the SAE E-32 Aerospace Propulsion Systems Health Management Committee as part of the Committee’s Master Plan.
CANCELLATION NOTICE
This Technical Report has been declared “CANCELLED” as of (MONTH YEAR WHEN PUBLISHED) and has been superseded by AIR46. By this action, this document will remain listed in the respective index, if applicable. Cancelled Technical Reports are available from SAE.